Multi-cathode display tube



April'26, 1966 DESPRls 3,248,589

MULTI-CATHCDE DISPLAY TUBE Filed D60. 5, 1963 2 Sheets-Sheet 1 P06 er/ DES PR/S ATTO 2 Sheets-Sheet 2 FIG 9 INVENTOR 1 P01) er/ 0E5 PR/S April 26, 1966 R DESPRIS MULTI-CATHODE DISPLAY TUBE Filed Dec. 5, 1963 FIG.1O

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United States Patent Ofiice The present invention relates to display tubes, and more particularly to improvements in multi-cathode character display tubes. 1

It is known that the so-called character display tubes comprise a stack of signs, characters or symbols which play the role of cathodes, usually disposed parallel to one another and electrically insulated from one another.

If one applies a direct-current voltage between the anode and one of these cathodes, a luminous sheath or envelope of rare ionized gas has to establish itself about all of the portions of the cathode which one desires to render visible to the exclusion of any connection or portions of this cathode that have to serve, for example, as

connection between useful elements.

The connections are generally realized heretofore, without great difliculties, with the aid of materials of which the working potential is very different from that utilized for the cathode. However, the problem is much more difficult when one is concerned with realizing signs,

. characters or symbols of complex geometry and where it is oftentimes necessary to provide mechanical connections between two or several elements of one and the same cathode, with the aim to rigidify the assembly, while these connections, on the other hand, should not appear luminous or visible in certain cases.

Furthermore, the support and fixing of the cathodes necessitates a certain number of attachment points, for example, by means of eyelets or fork-like elements which are stacked on a certain number of insulated metallic rods. This number of attachment points is normally the larger the more complex the figure represented by the cathode.

The object of the present invention is a character display tube, intended in particular to display symbols of complex geometry, in which the envelope of ionized gas within the regions of the cathode that are not to become visible, is suppressed, and in which additionally the support and fixing of the cathode necessitate only tachments.

According to the present invention, each symbol to be displayed within the tube according to the present invention is surrounded by a metallic frame to which it is secured in a desired number of points, whereby the assembly of the symbol and of the frame are a unitary piece of manufacture; this frame is provided with stacking means on only two insulated rods and is mounted in sandwich-fashion between two insulating frames of the same shape as the metallic frame, these insulating frames being eventually provided with tongues intended to mask the portions of the cathodes of which the visibility is undesired.-

Accordingly, it is an object of the present invention to provide a multi-cathode character display tube which eliminates by extremely simple means the drawbacks and shortcomings encountered with the prior art tubes of similar nature.

It is another object of present invention to provide a unitary cathode subassembly for a multi-cathode character display tube which permits the use of symbols of complex geometry yet allows by extremely simple and reliable means, a suppression of the ionized gas envelope two at- 3,248,589 Patented Apr. 26, 1966 near those parts of the cathode, particularly the connections thereof with the supports which one desires to keep invisible.

Still a further object of the present invention resides in the provision of a multi-cathode display tube which results in a sturdy and rigid assembly, notwithstanding the use of a relatively large number of stacked cathodes and a small number of supports.

A further object of the present invention resides in the provision of a multi-cathode character display tube which utilizes only two support means for each cathode yet assures a sturdy cathode assembly for cathodes of complex geometry.

Still another object ofthe present invention resides in the provision of a multi-cathode character display tube of the type described hereinabove which permits a simple assembly into a rigid unitary structure of a plurality of unitary, integral cathode and frame subassemblies.

These and other objects, features and advantages of the present invention will become more obvious fromthe following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein:

FIGURES 1 to 5 are elevational views of some examples of complex symbols in accordance with the present invention, cut out in a single piece together with the metallic frame; I

FIGURE 6 is an elevational view of an insulatin frame in accordance with the present inventionintended to mask the metallic frame in the assembled condition;

FIGURE 7 is an elevational view of a modified embodiment of an insulating frame in accordance with the present invention, adapted in particular to the symbol of FIGURE 3;

FIGURE 8 is a transverse cross sectional view of an assembly comprising a metallic frame assembled in sandwash-fashion between two insulating frames in accordance with the present invention;

FIGURE 9 is a transverse cross sectional view, similar to FIGURE 8, of a modified embodiment of an assembly comprising a metallic frame mounted in sandwichfashio-n between two insulating frames in accordance with the present invention, and

FIGURE 10 is an elevational view of an illuminated cathode in accordance with the present invention.

Referring now to the drawings wherein like reference numerals are used throughout the various views to designate like parts, FIGURES 1 through 5 represent illustrative examples of different characters such as the W, DM, NF of the symbols of the dollar or of the pound sterling, respectively. Each of the characters or symbols of FIGURES 1 through 5 forms a unitary piece with a frame 1 in the form of a circular rim provided with two eyelets 2 that are disposed diametrically opposite one another. Each piece may be realized by conventional cut out from a foil or sheet of any metal known for its applicability to such cathodes or by photoforming or any other conventional known process.

FIGURE 6 illustrates an insulating ring or washer 3, for example, made of mica or ceramic, and adapted for use with the frame of FIGURES 1, 2, 4 and 5. The insulating washer 3 is provided with two diametrically opposite bores or apertures 4 of which the location and spacing corresponds to that of the eyelets 2. The dimension d of the circumference of the washer 3 is equal to 2 to 2.5 times the dimension s of the frame. The thickness of the washer 3, in the direction perpendicular to its plane, may be about 0.3 to 0.35 mm.

The insulating washer of FIGURE 7 differs from that of FIGURE 6 by the presence of a tongue 5. This insulating washer 3 is adapted for use with the symbol of 3 FIGURE 3 and the tongue 5 is then intended to mask the connection 6 between the letters N and F, a connection which one desires to render invisible.

FIGURE 8 shows in transverse cross-section the assembly of a desired number of symbol-s within the tube. Each frame 1 is assembled in sandwich-fashion between two insulating washers 3, all of these elements being aligned and mounted on two insulating rods such as 7 extending through the respective apertures 2 and 4.

FIGURE 9 differs from FIGURE 8 only by the presence of a supplementary insulating pieces 8 of ceramic material which one interposes between the successive pieces 3 in case one would estimate that the insulation assured by the Washers 3 is not sufficient.

In operation, the portions not covered by the thickness of the insulating material becomes luminous, and those masked by the elements of the insulating rings or washers remains invisible. For example, FIGURE 10 illustrates the superposition of pieces according to FIG- URES 3 and 7, and those parts which are illuminated and visible from the outside are indicated therein by the cross-hatching.

While I have shown and described several embodiments in accordance with the present invention, it is understood that the same is not limited thereto, but is susceptible of numerous changes and modifications within the scope of a person skilled in the art. For example, the metallic frame need not be circular as shown, but may also cover the form of a triangle,'a rectangle, a square or any other geometric plane figure or shape. However, it is understood that the insulating pieces in all of these cases will then have to represent exactly the portions of the cathodes which should not become ionized in operation.

Thus, it is obvious that the present invention is susceptible of numerous changes and modifications within the spirit and scope thereof, and I therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

I claim: 1. A multi-cathode structure for use in a multi-cathode character display tube, comprising:

a plurality of cold cathodes each in the form of a predetermined character, a frame of the same metal as said character and surrounding a respective cathode, each frame being connected to a corresponding character in at least two points, and each frame and character assembly being constituted by an integrally formed piece, each frame being provided with a pair of holes for passing therethrough supporting means, and supporting means including a pair of insulating rods extending through said holes, the cathode and frame assemblies being stacked in such a manner that said rods pass through the pair of holes in each of said frames, and insulating washers, successive cathodes being each located sandwich-wise between two insulating washers, each insulating washer being substantially of the same shape as said frames whereby said frames are masked and the illumination thereof is precluded during operation of the tube. 2. A multi-cathode structure for use in a multi-cathode character display tube, comprising:

a plurality of cold cathodes each in the form of a predetermined character, a frame of the same metal as said character and surrounding a respective cathode, each frame being connected to a corresponding character in at least two points, and each frame and character assembly being constituted by an integrally formed piece, each frame being provided with a pair of holes for passing therethrough supporting means,

and supporting means including a pair of insulating rods extending through said holes,

the cathode and frame assemblies being stacked in such a manner that said rods pass through the pair of holes in each of said frames, and insulating washers,

successive cathodes being each located sandwich-wise between two insulating washers, each insulating washer being substantially of the same shape as said frames whereby said frames are masked and the illumination thereof is precluded during operation of the tube,

said insulating washers being each provided with a pair of holes in alignment with the pairs of holes in said frame to enable said supporting rods to pass therethrough.

3. A multi-cathode structure for use in a multi-cathode character display tube, comprising:

a plurality of cold cathodes each in the form of a predetermined character,

a frame of the same metal as said character and surrounding a respective cathode,

each frame being connected to a corresponding character in at least two points,

and each frame and character assembly being constituted by an integrally formed piece,

each frame being provided with a pair of holes for passing therethrough supporting means,

and supporting means including a pair of insulating rods extending through said holes,

the cathode and frame assemblies being stacked in such a manner that said rods pass through the pair of holes in each of said frames,

and insulating washers,

successive cathodes being each located sandwich-wise between two insulating washers, each insulating washer being substantially of the same shape as said frames whereby said frames are masked and the illumination thereof is precluded during operation of the tube,

at least some of said insulating washers being provided within the vicinity of a predetermined character with tongue portions for masking predetermined portions of the corresponding character thereby precluding illumination of said portions during operation of the tube.

4. A multi-ca'thode structure for use in a multi-cathode character display tube, comprising:

a plurality of cold cathodes each in the form of a predetermined character,

a frame of the same metal as said character and surrounding a respective cathode,

each frame being connected to a corresponding character in at least two points,

and each frame and character assembly being constituted by an integrally formed piece,

each frame being provided with a pair of holes for passing therethrough supporting means,

and supporting means including a pair of insulating rods extending through said holes,

the cathode and frame assemblies'being stacked in such a manner that said rods pass through the pair of holes in each of said frames,

and insulating washers,

successive cathodes being each located sandwich-wise between two insulating washers, each insulating washer being substantially of the same shape as said frames whereby said frames are masked and the illumination thereof is precluded during operation of the tube,

and additional insulating pieces inserted between two adjacent insulating washers.

5. A multi-cathode structure for use in a multi-cathode character display tube, comprising:

a plurality of cold cathodes each in the form of a predetermined character,

a frame of the same metal as said character and surrounding a respective cathode,

the cathode and frame assemblies being stacked in such a manner that said rods pass through the pair of holes in each of said frames,

and insulating washers,

each frame being connected to a corresponding charac- 5 successive cathodes being each located sandwich-wise ter in at least two points, between two insulating washers, each insulating and each frame and character assembly being conwasher being substantially of the same shape as stituted by an integrally formed piece, said frames whereby said frames are masked and the each frame being provided with a pair of holes for illumination thereof is precluded during operation of passing therethrough supporting means, 10 the tube,

and supporting means including a pair of insulating said insulating washers being each provided with a pair rods extending through said holes, of holes in alignment with the pairs of holes in said the cathode and frame assemblies being stacked in frame to enable said supporting rods to pass theresuch a manner that said rods pass through the pair through, of holes in each of said frames, at least some of said insulating washers being proand insulating washers, vided within the vicinity of a predetermined characsuccessive cathodes being each located sandwich-wise ter with tongue portions for masking predetermined between two insulating washers, each insulating portions of the corresponding character thereby washer being substantially of the same shape as said precluding illumination of said portions during opframes whereby said frames are masked and the il- 0 eration of the tube, lumination thereof is precluded during operation of and additional insulating pieces inserted between two the tube, adjacent insulating washers.

said insulating washers being each provided with a pair 7. A multi-cathode structure for use in a multi-cathode of holes in alignment with the pairs of holes in said character display tube as defined in claim 1 wh i frame to enable said supporting rods to pass theresaid insulating washers are each constructed as rigid elements.

8. A rnulti-cathode structure for use in a multi-cathode character display tube as defined in claim 1 wherein said insulating washers are each made of a ceramic material.

through, and additional insulating pieces inserted between two adjacent insulating washers. 6. A multi-cathode structure for use in a multi-cathode character display tube, comprising:

a plurality of cold cathodes each in the form of a pre- References Cited by the Examiner determined character, UNITED STATES PATENTS a framecf the same metal as said character and sur- 988,104 3/1911 Jenckes mundmg aiespectlve cathode 1,560,103 11/1925 Schmierer 313-1095 each frame being connected to a corresponding charac- 2,848,638 8/1958 smith at least two Pom, 2,874,320 2/1959 Jampel 313 1o9.5

and each frame and character assembly being con 2,878,407 3/1959 Engelman et aL 313*109'5 stmted by an mtegmny firmed P16, 3,075,119 1/1963 Botden et a1 31s 109.5

each frame being provided with a pair of holes for passing therethrough supporting means,

and supporting means including a pair of insulating rods extending through said holes,

JOHN W. HUCKERT, Primary Examiner.

DAVID J. GALVIN, Examiner. 

3. A MULTI-CATHODE STRUCTURE FOR USE IN A MULTI-CATHODE CHARACTER DISPLAY TUBE, COMPRISING: A PLURALITY OF COLD CATHODES EACH IN THE FORM OF A PREDETERMINED CHARACTER, A FRAME OF THE SAME METAL AS SAID CHARACTER AND SURROUNDING A RESPECTIVE CATHODE, EACH FRAME BEING CONNECTED TO A CORRESPONDING CHARACTER IN AT LEAST TWO POINTS, AND EACH FRAME AND CHARACTER ASSEMBLY BEING CONSTITUTED BY AN INTEGRALLY FORMED PIECE, EACH FRAME BEING PROVIDED WITH A PAIR OF HOLES FOR PASSING THERETHROUGH SUPPORTING MEANS; AND SUPPORTING MEANS INCLUDING A PAIR OF INSULATING RODS EXTENDING THROUGH SAID HOLES, THE CATHODE AND FRAME ASSEMBLIES BEING STACKED IN SUCH A MANNER THAT SAID RODS PASS THROUGH THE PAIR OF HOLES IN EACH OF SAID FRAMES, AND INSULATING WASHERS, SUCCESSIVE CATHODES BEING EACH LOCATED SANDWICH-WISE BETWEEN TWO INSULATING WASHERS, EACH INSULATING WAHSER BEING SUBSTANTIALLY OF THE SAME SHAPE AS SAID FRAMES WHEREBY SAID FRAMES ARE MASKED AND THE ILLUMINATION THEREOF IS PRECLUDED DURING OPERATION OF THE TUBE, AT LEAST SOME OF SAID INSULATING WASHERS BEING PROVIDED WITHIN THE VICINITY OF A PREDETERMINED CHARACTER WITH TONGUE PORTIONS FOR MASKING PREDETERMINED PORTIONS OF THE CORRESPONDING CHARACTER THEREBY PRECLUDING ILLUMINATION OF SAID PORTIONS DURING OPERATION OF THE TUBE. 